Paper manufacture



-',lo Drawing.

.of the principle Patented June 20, 1933 HAROLD nom'r RAMON AND ARTHUR MINABD BROOKS,

BAI'FOLD PROCESS CORPORATION,

OF ANDOVER, MASSACHU- A CORPORATION OI KAS- PLPER EANUFACTUBE Application filed Kay 4,

This invention relates to the manufacture of paper and more particularly to the manufacture of paper filled with alkaline filler.

The principal ob'ect of this invention is the manufacture o sized paper filled with alkaline filler.

An important object is the use of rubber as the sizing agent.

A further ob ect is the employment of rubher in conjunction with rosin size as the sizing agent.

A further object is the employment of the princi le of adding materia s under conditions avoring the minimizin of the time and/or intimacy of contact 0 the constituents of the mix in connection with the sizing with rubber of paper filled with alkaline filler.

A further object is the employment of heat in the development of the sizing in paper sized with rubber and'filled with alkaline filler.

A further object is the use of rubber or rubber-like materials containing softeners or materials which lower their melting and/or softening point.

Other objects and advantages of this invention will become apparent during the course of the following description.

It is well known that paper sized with rosin size in the ordinary manner will not serve to produce satisfactorily sized paper filled with alkaline filler. Special methods, however. have been developed for this purpose which are disclosed in numerous copendingapplications of Rafton. A number of these methods are practical embodiments of minimizing the time and/or intimacy of contact of the constituents of an alkaline filler paper mix. Other methods involve the use of a hydrocarbon substantially inert to acidic and alkaline materials such as parafiine or the like, employed jointly if desired with one or more embodiments of the minimizing principle mentioned above.

It has hitherto been proposed to use rubber in paper mixes particularly in the form of dispersions such as natural latexes or artificial aqueous dispersions, but it has never been Serial K0. 535,087.

previously disclosed that such dispersions of rubber are suitable for sizing paper filled with alkaline filler. However we have now found that under certain conditions they will so serve.

The prior disclosed uses of rubber dispersions havebeen alleged to impart certain rubber-like qualities to the paper made therefrom, but the sizing effect obtained when rubber dispersions have been used in amounts which customarily are employed when rosin sizing is used for sizing paper, e. g. in the neighborhood of a few percent, has been rather poor. We have found, however, that even the relatively poor sizing which is obtained from the use of rubber in paper mixes is substantially deteriorated by alkaline filler, resulting in substantially unsized paper being produced therefrom. Practically the same result is obtained with rubber and alkaline filler as when rosin size is used therewith in the ordinary manner as referred to above.

We have found, however, that if rubber be incorporated into a fibrous mix with alkaline filler, applying the embodiments of the minimizing principle as set forth in the vari'ous-Rafton applications, that sized paper filled with alkaline filler and with rubber as a sizing agent can be produced.

We with alkaline filler and containing rubber, and which are substantially unsized, because the embodiments of the minimizing principle were not employed in the manufacture thereof, may be converted in some degree into sized papers by aging. We have also found that this process may be accelerated and improved by the application of moderate heat, and greatly accelerated and improved by the application of still higher temperatures. T us papers containing alkaline filler and rubber which are substantially unsized have further found that papers filled can be subjected to a temperature of, for example, from 140-150 (3., and converted into sized paper. While this may be conducted as an operation independent of the papermaking operation, it is not necessary so to do, as this heating can be applied during the course of manufacture of the paper on the paper machine by suitable means.

destruction of the effect maintained by such to the rial. ddition of one- As will be apparent, ieating to such a temperature usually requi-ies special apparatus and may in certaincas'es injure the fibrous material. We have found, however, that if modifying or softening agents be added to the rubber, such as those which cause it to melt, soften or spread at a lower temperature, that sizing in paper filled with alkaline filler may be obtainedat a temperature such as will not substantially injure the fibre. Likewise by using other rubber-like materials which melt, soften or spread at a lower temperature than rubber, such-as balata, gut-ta-percha, chicle or the like, satisfactory .sizin may be obtained at substantially non-injurious temperatures. It will be understood that modi-v fying or softening agents may likewise be applied to these last mentioned rubber-like materials with beneficial results. -By these methods greatly improved sizingresults may be obtained in papers filled fillers.

In Raftons various copending applications he has discussed in full the basis of the minimizing principle, which phrase merely serves as an abbreviation of the longor expression minimizing the time and/or intimacy ofcontact of the constituents of the mix. Briefiyit is that alkaline filler which always is present in the stock from which pa-' per filled with alkaline filler is made in great stoichiometrical excess over the acidic constituent acts upon the acidic constituent to the ultimate destruction thereof and/or the constituent. (The acidic constituent may be one which is actually acid, and/or one which, such as a size precipitate is capable of being affected or deteriorated by an alkaline material.) The action just referred to has been found to depend upon the time of contact of the acidic and alkaline constituents and also upon the intimacy of contact of these constituents. Agitation such as normally occurs in papermaking procedure in stuff chests or the like accelerates the rate of reaction but agitation at low concentrations while havin some eifect is not nearly so deleterious. ased on this principle a practical application has been developed whereby by minimizing the time and/or intimacy of contact of the acidic and alkaline constituents, the acidic constituent'and/or effect produced thereby is substantially preserved in an alkaline filler mix.

With the present types of paper machines and the present arrangementof apparatus usually employed in paper machine operatlon, the contact of the acidic materialiand the alkalne constituent at any time prior passage'of the stock from the last stufi chest, which is. commonly-called the machine chest, results in great deterioration or com lete destruction of the acidic mateor bothof these conwith alkaline stituents at a point subsequent to the passage of the stock from the machine chest, after which point according to present day operating practice the stock remains in concentrated condition only for a very brief in.- teijva-l of time, or addition preferably at or subsequent to the point of dilution, that is, at the wet end of the paper machine, serves to substantially conserve the acidic material and or effect thereof in thefibrous mix.

We have found that the precipitated rubber in an alkaline filler mix or the precipitated rubber in combination or association with the precipitant, although it may not actually be acid, acts very similarly to the acidic material and ordinary size precipitates referred to above as its sizing effect is similarly deteriorated. However by utilizing the various procedures based on the minimizing principle as set forth in the above referred to Rafton copending applications, suitable sizing effect can be obtained. Enumerating these various procedures, there are involved among others the following illus-- 9G tra tive combinations Ilius- I tra- tive Materials added at dilute mm M atarials added in beater stage bination a R #1 glibrous material Restoring agent to Slzeaprecl itant 'Alk line la: #2 Fibrous material Size precipitant m Alkaline iilier #3 Fibrous material Size Alkaline filler Size precipitant l4 Fibrous material Size iprecipitated by size Alkaline filler rec pitant #5 gibrous material Al aiine filler in Size precipitant I6 Fibrous material Size Size precipitant Alkaline filler f7 Fibrous material Size reci itant Size Alkaline Her #8 Fibrous material Size Size eci itant Alk ine ller I9 Fibrous material Sizt ptrgscnipitaied by size pro- 0 pi t Alkaline iiiier cedures also disclosed in Raftons copending,

applications involving the general minimizing principle such as protecting alkaline filler by precipitatingthereu on a temporal-i1 protecting precipitate suc as size recipitated by alum; temporarily reducing the pH of an alkaline filler by the addition of alum there'- to; the incorporation of sizing in the paper web; theincorporation of. filler in the paper web; and the like. All these procedures are applicable to the use of rubber-in paper filled with alkaline filler. Thus in the present invention, where we refer to size in the illustrative combinations and in this. paragraph, such size comprises rubber as'defined herein, or rubber in i set forth later herein.

combination withother sizes as 1 Where we. speak of the use of rubber in paper manufacture what we mean is the use of rubberdispersions preferably aqueous, which are ca able of being mixed with a paper mix an /or applied to a web while the latter are in aqueous or wet condition. Such dispersionsmay be natural latexes or mixtures thereof, or artificially compounded naturallatexes, or artificially prepared rubber dispersions, suitabl preserved if desired, a number of which are known. When we use .the wordrubber we mean to include any rubber-like material such as substantially water insoluble gums such as chicle, balata, gutta percha, or rubber, or substances containing or comprising rubber or rubber-like material, either natural or synthetic. We mean also to include compounds of rubber or rubber-like material, and materials which produce rubber or rubber-like material vhen suitably treated, such as in'the paper mix or in the drying and/or heating of the paper. It should be understood, however, that the word compounds as used in the previous sentence as referrin to rubber or rubber-like material does not ave the same meaning as it has in certain other places in this specifi-f cation where it, (or the associated adjectival form compounding, is used to refer to what is known colloquially in the rubber art as a compound, i. e. a 11111 of rubber, fillers, softeners, vulcanizing agents and the like which is blended as in a'rubber compounding mill and thenundergoes final treatment to convert it into a final rubber or rubber-like article; on the contrary, the word is used in the previous sentence in; its scientific meaning which includes any chemical or physico-chemical combination or association of rubber or rubber-like material with any element or chemical group or grouping, as well as any derivative thereof or of the original rubber or rubber-like material, and any associated molecular species such as polymer, isomer, tautomer, or the like. i

In the preferred practice of our invention we start with fibrous material. To this a rubber dispersion may be added in the beater,

or, in accordance with the various combinations and procedures referred to above,'the rubber dispersion may be added at the dilute stage, or applied in they web. There may also be added a precipitant for the rubber dispersion or one need not be added. The absence ofsuch precipitant will not result in the rubber dispersion being lost "from the aper mix in the white water owing to it not being coagulated in the paper mix, because we have found that in general alkaline'filler itself coagulates rubber dispersions. However a precipitant may be added-with advantage in certain cases, and this may be added as noted in the several combination'sand procedures outlined above'either in the concen condition, or in the dilute stage, or in the web. In the cases where no size precipitant is desired to be used, the various combinations and procedures referred to above may still be employed, the only difference being that the size precipitant is omitted in such cases.

To illustrate concretely one specific example, fibrous material, alkaline filler and a rubber dispersion may be mixed-in the beater and alum added thereto. The mix may pass throu h the various preparing machinery until it reaches the mixin box preparatory to passage on to the we -forming device. Preferably at this point or subsequent thereto is added a further quantit of alum which restores the sizing imparted by the rubber. The amount-of alkaline filler used may vary as desired, for example, it ma be approximately 15-20% of the furnis the rubber may be about 24% on the dry basis, the original alum added ma be about 3%, and the restoring alum adde may be about 3%. These figures as well as others given herein are understood to be illustrative only and not limiting, as we have found various other roportions to be suitable for our purpose. t will be apparent, however, that where we use. the expression paper filled with alkaline filler we mean lled paper which contains as an ingredient alkaline filler in appreciable amount, i. e. in an amount not less than thatof the rubber present.

' It' will be understood that size or sizings other than rubber may be employed in combination with the ru ber in practicing the various combinations and procedures outlined herein. Rosin size may with particular advantage be so employed. Wax emulsions, particularly-paraflin wax emulsions, especia 1y rosin size-paraflin emulsions,jmay also be employed with advanta e.

One of the modifications w%ierein rosin size may be particularlyadvantageously emalum, and the same added promptly at the wet end of the paper machine to a fibrous mixcomprising fibre sized with rosin size and alum in the beater. We have disclosed above that rubber-containing substantially unsized paper filled with alkaline filler, made without the emloyment of the minimizin principle, ma.

converted to sized paper y agin' or pre erablyby heat. These procedures ave also been found to improve the sizin of rubber containin sized paper filled w th alkaline filler, whlch have been'madeein accordance with the minimizing principle. It is to be noted that the heating action may in some cases require an interval of time to develop, and hence several heating rolls are referably used, or the pa or may pass t rough a heated chamber. f course the same result may be obtained after the manufacture of the paper by putting the paper through a special heating process.

As stated above when employing rubber with softening agents the temperature necessary to be obtained is reduced, and may be in many cases obtained directly on the paper machine without additional apparatus.

At times,.especially when the temperature desired to be used is such as to tend to injure the fibrous material, such injury may be substantially lessened or even eliminated by conducting the heating in the presence of a substantially inert gas or even in a vacuum; or steamor other heating or curing means or procedures, including the application of pressure, may be employed which in some in stances serve to reduce the temperature 25 required.

Our invention may be used with or with' out vulcanizing agents. The vulcanizing agents may be separately. incorporated in the paper mix or may he originally incorporated in the rubber dispersion, either with the already dispersed rubber, or directly with the rubber before the dispersion thereof if an artificial dispersion be employed. Sof.euing agents may be added either inthe paper mix, or blended directly with the rubber dispersion. Better results at times, however, seem to be obtained when the softening agent is added to the rubberprior to its dispersion, especially when artificial dispersions are employed. We may also if desired use accelerators or super-accelerators, a variety of which are well. known, and these may be incor porated in various manners as indicated above. Aswill be understood the/rubber may if desired be modified with other modifying or compounding agents ordinarily employed in compounding rubber.

As stated above in addition to rubber any oiher sizes suitable for use in paper may be employed,'the most common of which is rosin size. Any proportions desired may be employed. Suchsizes may be added to the paper mix with the rubber dispersion or independently as desired. Suchsizes usually require precipitation such as with alum, in order to be rendered effective in the paper. One

method' wh'ich may be employed is to melt rubber and rosin together in the desired proportions, or to dissolve them in a common solvent, andpreferably evaporate the solvent, and then emulsifyin alkali. This gives a rubber-rosin size dispersion. In making up such a dispersion the modifyin softening, vulcanizing or other agents 'may be blended.- with the original rubber or rubber-rosin mix.

salts.

'proportioning devices, screens, head boxes, inlets and the lik 130 In some cases it has been found t at the presence of sizes other-than rubber materially assisted in attaching the rubber to the fibres.

The preferred precipitant for the rubber and/or other size is alum, but a number of others may be employed, which need not be acidic for instance soluble salts of the alkaline earth 1net als,.or of other metals, or acidic materials such as acetic acid or other organic or mineral acids,or acid or acid reacting Any precipitant for rubber dispersions may serve. \V e employ the word piecipitant as synonymous with coagulant and as embracing agglo'nieiant .As examples of softening agents 'sultably employed may be mentioned petrolatum, stearic acid, cumarone resin, cottonseed oil, linseed oil, and the like, a variety of which are well known.

The term paper mix as used herein is. intended to mean a mix of various consiituents including fibre from which paper. may be made, either alone or after the addition of other ingredients.

By the term alkaline filler we mean substantially water insoluble filler which when agitated in contact with freshly boiled distilled water, say for an hour, will impart a pH value to such water greater than 70 that is, which will be on the alkaline side of the neutral point. Among fillers included in this group may be mentioned calcium carbonaie, of which lime mud from the causticizin process is one form; calcium carbonate magnesium. basic carbonate employed in the 9 paper disclosed in Raftons 5. Patent No; 1,595,416 of August 10, 1926;. calcium carbonate magnesium hydroxide disclosed in Raftons U. S.1Patent' No. 1,415,391 of May 9, 1922; and other substantially water insolum5 ble normal or basic carbonates of alkaline earth metals, (which expression is herein intended to include magnesium), or compounds, double salts, or physically associated mixtures of these with one 01; more other'acid no soluble materialsof a substantially water in soluble natur v When weuse the word paper. herein, we use it in the broad sense to include prodacts of manufacture of all "types and of'all weights and thicknesses, which containas. an essential constituent a considerable amount of prepared fibre and which are capable of bein produced on a Fourdrinier, cylinder, or ot. er forming, felting, shaping or: molding machine.

By the termfwet end of the'paper mil-- chine, we intend 'to include those instrumentalities employed in papeemanufacture by. which and/orin which a relatively con--. .centrated paper mix is diluted, and treated, conveyed or fed up tothe ointof web-forma tion, such asthe mixing. ox, regulating and rifile'rs, troughs,

eluding those instrumentalities useu in the white water cycle.

Where in the claims we use the word web, we mean to include not only the already formed web, after it has left the web-forming device, but also the forming web as it exists at an point on the web-forming device.

It is to be understood that our invention is not dependent upon or limited by any theory expressed herein.

We are aware that rubber has previously been compounded with alkaline materials that such compounded rubber has been aqueously dispersed, that rubber has been dispersed with alkaline agents, and other like procedures have been described; but so far as we know it has never been proposed to use aqueous rubber dispersions added in the liquid pulp or to the web in relatively minor proportions to produce a sized (i. e. ink-resistant) paper containing as filler alkaline filler in an amount not less than, or in excess, and normally in considerable excess, of the rubber present.

We have referred to various copending applications of Rafton above. Cross reference is hereby made particularly to the following: application Serial No. 262,030, filed March 15, 1928, now matured into Patent No. 1,819,- 441, issued August 18, 1931; application Serial No. 304 167, filed September 5 1928; application Serial No. 304,168, filed September 5, 1928; application Serial No. 304,170, filed September 5, 1928; application Serial No. 304,172, filed September 5, 1928; application Serial No. 304,173, filed September 5,

1928; application Serial No. 304,175, filed September 5, 1928; application Serial No. 304,176, filed September 5 1928; application Serial No. 304,177, filed September 5, 1928, now matured into Patents Nos. 1,803,642; 1,803,643; 1,803,645; 1,803,647; 1,803,- 648; 1,803,650; 1,803,651 and 1,803,652, respectively, all issued May 5, 1931; a plication Serial No. 319,719, filed November 15, 1928; application Serial No. 319 720, filed November 15, 1928; application Serial No. 319,721, filed November 15, 1928; application Serial No. 321,753, filed November 24,

1928; application Serial No. 321,754, filed November 24, 1928, now matured into Patents Nos. 1,808,067-71, respectively, all issued June 2, 1931; application Serial No. 353,668, filed April 8, 1929, now matured into Patent No. 1,848,659, issued March 8, 1932; application Serial No. 428,231, filed February 13, 1930; application Serial No. 440,645, filed March 31, 1930; application Serial No. 501,- 674, filed December 11, 1930; application Serial No. 533,571, filed April 28 1931; ap-

plication Serial No. 533,872, filed April 29,

1931; application Serial No. 534,461, filed May 1, 1931; application'Serial No. 534,462,.

filed May 1, 1931.

Whereas we have described in detail the ried without departing from the 8%11'16 of size precipitate preferred embodiments of our invention, it is to be understood that the details of procedure, the proportions of ingredients, and the arrangement of steps may be widely vaour invention or the scope of the su claims.

We claim:

1. Paper filled with alkaline filler comprisfibrous material, rubber, and alkaline 2. Sized paper filled with alkaline filler comprising fibrous material, rubber, and alkaline filler.

3. Paper filled with alkaline filler com- I prising fibrous material, precipitated rubber, and alkaline filler.

4. Paper filled with alkaline filler com rising fibrous material, rubber, and a modi ying agent therefor, and alkaline filler.

5. Paper filled with alkaline filler comprising fibrous material, rubber, and alkaline filler, said rubber comprising balata.

6. Paper filled with alkaline filler comprising fibrous material, rubber, and alkaline filler, said rubber comprising gutta percha.

7. Paper filled with alkaline filler comprisin fibrous material, rubber, and alkaline fil cr, said rubber comprising chicle.

8. Paper filled with alkaline filler comprising fibrous material, rubber, vulcanizing material, and alkaline filler.

9. Paper filled with alkaline filler comprising fibrous material, rubber, and a softening agent therefor, and alkaline filler.

10. Pa r filled with alkaline filler comprising fi rous material, rubber, and alkaline filler, said alkaline filler comprising calcium carbonate.

11. Paper filled with alkaline filler comprising fibrous material, rubber, and alkaline filler, said alkaline filler comprislng calcium carbonate and magnesium compound.

12. Pa r filled with alkaline filler comprising fi rous material, rubber, and alkaline 1 0 filler, said akaline filler com rising calcium carbonate magnesium hydroxide.

13. Sized paper filled with alkaline filler comprising fibrous material, rubber, and alkaline filler, said alkaline filler being pres- 1, 6 ent in excess of said rubber.

14. Sized paper filled with alkaline filler comprising fibrous material, rubber, size, and alkaline filler.

15. Sized paper filled with alkaline filler comprising fibrous material, rubber, precipitated size, and alkaline filler.

16. Sized paper filled with alkaline filler comprising fibrous material, rubber, precipitated rosin size, and alkaline filler. 1

17. Sized paper filled with alkaline filler comprising fibrous material, rubber, rosin d by alum, and alkaline filler.

18. Sized aper filled with alkaline filler comprising, brous material, rubber, precip joined ita'ted rosin size, and alkaline filler, said alkaline filler being present in excess of said rubber.

19. A method of manufacturing sized paper filled with alkaline filler characterized by the inclusion in a paper'furnish of alkaline filler and rubber. 20'; A method of manufacturing sized paper filled with alkaline filler characterized by the inclusion in a paper furnish of alkaline filler, rubhmgand a precipitant.

21. A 7 method of manufacturing sized paper filled with alkaline filler characterized y the inclusion in a paper furnish of alkaline filler, rubber, and size.

22. A method of manufacturing sized paper filled with alkaline filler characterized V the inclusion in a paper furnish of alkaline filler, rubber, size, and a preci itant.

23. A method of manufacturing sized paper filled with alkaline filler characterized by the inclusion in a paper furnish of alkaline filler, rubber, and rosin size.

24. A method of manufacturing sized paper filled with alkaline filler characterized by the inclusion in a paper furnish of alkaline filler and rubber, and the applying of heat sufiicient to develop sizing in said paper.

25. In a method of manufacturing s zed paper filled withalkaline filler in which material is added under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, that stepcomprising the inclusion of rubber in the paper mix.

26. In the method of manufacturing sized paper filled with alkaline filler in which material is added under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, those steps comprising'the inclusion of rubber and a precipitant in the paper mix.

27. In a method of manufacturing sized paper filled with alkaline filler in which material is added under conditions favoring the minimizing of the time and/or intin acy of contact of the constituents of the m-ix,,those steps comprising the inclusion of rubber and size in-the paper mix.

28. In the method of manufacturing sized paper filled with alkaline filler in which material is added under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, those steps comprising the inclusion of rubher, size, and precipitant in the paper mix.

29. In a method of manufacturing sized paper filled with alkaline filler in which material. is added under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, those steps comprising the inclusion of rubber and rosin size in the paper mix.

3:0.v In a method of manufacturing sized paper filled with. alkaline filler in which. ma-

terial is added under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, those steps comprising the inclusion of rubber and rosin size and a precipitant'therefor in the' Ill 

